Iron sand or iron ore?

Primarily iron sand was used as the source of iron in early modern iron manufacturing. There are many instance from ancient times, however, in which iron ore was used. The map below shows the distribution of ironworks ruins from ancient to medieval times throughout the Chugoku region, and the iron source used at each. Iron ore was used on the San'yo side of the region in ancient times (especially in the Bizen, Bichu, and Bingo areas) and, though not shown here, was also limited to the area around Lake Biwa (near Kyoto). Iron sand was used in most areas of the San'in region (western Honshu along the Sea of Japan encompassing Tottori, Shimane, and Yamaguchi prefectures, as well as the northern portions of Kyoto and Hyogo prefectures) and elsewhere. This may indicate that there were differences in the route along which iron manufacturing technology spread.

Source of Iron in Ancient to Medieval Period Ironworks Sites

Furnace Shape

Furnaces were found in a variety of shapes by the Kofun Period, including circular, elliptical, square, and rectangular. By the ancient period (8th-9th century) a rectangular chamber furnace had become more or less standard. On the other hand, from the early 8th century, half-buried, vertically oriented furnaces appeared in Japan's eastern provinces (the area around modern Tokyo). The style spread in the 9th century to areas along the Japan Sea coast. Ironworks furnaces of this gradually became representative of eastern Japan, and it is known that in the 10th century had spread even to Kyushu. These vertical furnaces were responsible for a region's self-sufficiency in iron production, but they disappeared in medieval times. How was it that this difference between eastern and western Japan in furnace shapes emerged? Are the roots of iron manufacturing different for the two areas? There are still many things that we do not know.

Distribution of Each Type of Ancient Ironworks Furnace

Source: TOSA Masahiko, “Kodai no seitetsu iseki [Remnants of ancient iron manufacturing]” (Symposium on Iron Manufacturing and Blacksmiths, Hiroshima University, December 1995)

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